Effects of a Single and Short-Term Ingestion of Diacylglycerol on Fat Oxidation in Rats

This study examines the effect of diacylglycerol (DAG) oil consisting mainly of 1,3-species on fat oxidation as a possible mechanism for anti-obesity. We examined the following: (1) the long-term (23-week) effects of a DAG oil diet on the development of obesity; (2) the effect of a single ingestion of DAG oil on fat oxidation; and, (3) the short-term (2-week) effect of a DAG oil diet on fat metabolism in rats. Rats fed a DAG oil diet accumulated significantly less body fat compared to rats fed a triacylglycerol (TAG) oil diet, each oil possesses a similar fatty acid composition. More ¹⁴C-CO₂ was expired and less ¹⁴C-radioactivity was incorporated into visceral fat after administration of a tracer emulsion containing 1,3-[oleoyl-1-¹⁴C] diolein compared to [carboxyl-¹⁴C] triolein. Indirect calorimetry showed respiratory quotients were significantly lower in the DAG oil diet group than in the TAG oil diet group. More ¹⁴C-CO₂ was expired and less ¹⁴C-radioactivity was incorporated into visceral fat in the DAG oil diet group than in the TAG oil diet group after a single intragastric administration of [carboxyl-¹⁴C] triolein. These results suggest the following. (1) DAG oil has an inhibitory effect on diet-induced fat accumulation. (2) 1,3-DAG, a major component of DAG oil, is more susceptible to oxidation. (3) A short-term ingestion of DAG oil increases fat utilization at the whole body level and results in increased oxidation of dietary fat. The stimulated fat oxidation might be one explanation for the anti-obesity effect of long-term DAG oil ingestion.